全文获取类型
收费全文 | 21334篇 |
免费 | 3644篇 |
国内免费 | 2746篇 |
专业分类
化学 | 15617篇 |
晶体学 | 265篇 |
力学 | 1218篇 |
综合类 | 191篇 |
数学 | 2935篇 |
物理学 | 7498篇 |
出版年
2024年 | 30篇 |
2023年 | 460篇 |
2022年 | 497篇 |
2021年 | 630篇 |
2020年 | 864篇 |
2019年 | 856篇 |
2018年 | 690篇 |
2017年 | 613篇 |
2016年 | 1042篇 |
2015年 | 1016篇 |
2014年 | 1313篇 |
2013年 | 1606篇 |
2012年 | 1935篇 |
2011年 | 2009篇 |
2010年 | 1401篇 |
2009年 | 1211篇 |
2008年 | 1383篇 |
2007年 | 1255篇 |
2006年 | 1179篇 |
2005年 | 1075篇 |
2004年 | 838篇 |
2003年 | 690篇 |
2002年 | 675篇 |
2001年 | 599篇 |
2000年 | 404篇 |
1999年 | 460篇 |
1998年 | 375篇 |
1997年 | 314篇 |
1996年 | 352篇 |
1995年 | 313篇 |
1994年 | 285篇 |
1993年 | 221篇 |
1992年 | 190篇 |
1991年 | 182篇 |
1990年 | 153篇 |
1989年 | 139篇 |
1988年 | 93篇 |
1987年 | 64篇 |
1986年 | 59篇 |
1985年 | 58篇 |
1984年 | 57篇 |
1983年 | 35篇 |
1982年 | 28篇 |
1981年 | 23篇 |
1980年 | 15篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1957年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
21.
Hu Yinlong Hua Tianyang Chen Michael Z. Q. Shi Shang Sun Yonghui 《Nonlinear dynamics》2021,105(1):99-112
Nonlinear Dynamics - In this paper, the instability of semi-active control systems caused by the utilization of semi-active inerters is analyzed. The purpose of this study is to demonstrate the... 相似文献
22.
Nonlinear Dynamics - In this work, the problem of hybrid control strategy for delayed neural networks is investigated via an impulsive-based bilateral looped-functional (IBBLF) approach. Firstly, a... 相似文献
23.
Theoretical and Mathematical Physics - By introducing shift relations satisfied by a matrix $$\boldsymbol{r}$$ , we propose a generalized Cauchy matrix scheme and construct a discrete second-order... 相似文献
24.
A general framework for describing photofission observables of actinides at an average excitation energy below 30 MeV 下载免费PDF全文
Guan-Lin Wang Hao-Yang Lan Xiao-Ming Shi Zhi-Chao Zhu Wen Luo 《中国物理C(英文版)》2022,46(8):084102-084102-14
A reasonable prediction of photofission observables plays a paramount role in understanding the photofission process and guiding various photofission-induced applications, such as short-lived isotope production, nuclear waste disposal, and nuclear safeguards. However, the available experimental data for photofission observables are limited, and the existing models and programs have mainly been developed for neutron-induced fission processes. In this study, a general framework is proposed for characterizing the photofission observables of actinides, including the mass yield distributions (MYD) and isobaric charge distributions (ICD) of fission fragments and the multiplicity and energy distributions of prompt neutrons (np) and prompt γ rays (γp). The framework encompasses various systematic neutron models and empirical models considering the Bohr hypothesis and does not rely on the experimental data as input. These models are then validated individually against experimental data at an average excitation energy below 30 MeV, which shows the reliability and robustness of the general framework. Finally, we employ this framework to predict the characteristics of photofission fragments and the emissions of prompt particles for typical actinides including 232Th, 235, 238U and 240Pu. It is found that the 238U(γ, f) reaction is more suitable for producing neutron-rich nuclei compared to the 232Th(γ, f) reaction. In addition, the average multiplicity number of both np and γp increases with the average excitation energy. 相似文献
25.
Journal of Solid State Electrochemistry - The effects of chemisorbed sulfate on the spatiotemporal dynamics of Na2S in strongly alkaline solutions were investigated via electrochemical measurements... 相似文献
26.
Wang Zenghao Xie Yongshuai Xu Chonghe Shi Shuying Wang Lin Zhang Guanghui Wang Xinqiang Zhu Luyi Xu Dong 《Journal of Solid State Electrochemistry》2019,23(1):269-276
Journal of Solid State Electrochemistry - Lithium-ion batteries have been receiving more and more attention because of the energy crisis. As an important subassembly of lithium-ion batteries, the... 相似文献
27.
Zhang Yi Huang Peng Long Mei Liu Song Yang Huaming Yuan Shuwen Chang Shi 《中国科学:化学(英文版)》2019,62(1):58-61
An innovative cancer therapy strategy regarding the interface engineering of kaolinite has been designed. The exposed silanol group facilitates more guest species with high dispersion on the supports. Mn_3O_4 magnetic nanoparticles are uniformly distributed on external surfaces of the Kaolin_(C12N)with the Al–O–Mn bond for the detection of the tumor microenvironment by T1-MRI; Doxorubicin(DOX) are loaded in the interlayer space with the electrostatic interaction for chemo-treating; and KI is coated on the outer layer of the nanocomposites based on the electrostatic interaction for thyroid cancer targeting. The synergetic effects and the treatment mechanism enhanced by the interface engineering, KI@DOX-Mn_3O_4-Kaolin_(C12N)can cause remarkably low cell viability(57%, 200 μg/mL), tumor shrinking(75%, 20 μg/kg), and accumulation into the tumor tissues. The novel kaolinite based drug delivery system is expected to incorporate imaging diagnosis, targeted therapy and drug delivery into one single system for postoperative residual thyroid cancer treatment and observation for metastasis of focal area. 相似文献
28.
Nonlinear Dynamics - This paper considers the distributed adaptive neural consensus tracking control problem for a class of uncertain nonaffine nonlinear multi-agent systems. By making use of the... 相似文献
29.
采用密度泛函理论的B3LYP, B3P86, B1B95, P3PW91和PBE1PBE方法结合SDD, LANL2DZ和CEP-121G基组计算了d~(10)组态二聚物MN(M=Ga, Ge, In, Sn和Sb; N=M和Al)的几何结构.采用B3P86/SDD进一步研究了MN@H_2O团簇的几何结构及吸附能.结果表明,水分子结合在二聚物M_2上时,对二聚物影响较大,对水分子自身影响较小.将M_2中Ga, Ge, In, Sn或Sb替换一个原子为Al时,水分子在GeAl和SnAl上的吸附能变化较大,而在GaAl, InAl和SbAl上吸附能变化较小.另外, H_2O吸附在Ga, Ge, In, Sn和Sb上时,与吸附在Al上时,吸附能的变化不大. 相似文献
30.
Ge Huang Prof. Li Yang Qi Yin Zhi-Bin Fang Xiao-Jing Hu An-An Zhang Prof. Jun Jiang Prof. Tian-Fu Liu Prof. Rong Cao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(11):4415-4420
Although many ionic metal–organic frameworks (MOFs) have been reported, little is known about how the charge of the skeleton affects the properties of the MOF materials. Herein we report how the chemical stability of MOFs can be substantially improved through embedding electrostatic interactions in structure. A MOF with a cationic skeleton is impervious to extremely acidic, oxidative, reductive, and high ionic strength conditions, such as 12 m HCl (301 days), aqua regia (86 days), H2O2 (30 days), and seawater (30 days), which is unprecedented for MOFs. DFT calculations suggested that steric hinderance and the repulsive interaction of the cationic framework toward positively charged species in microenvironments protects the vulnerable bonds in the structure. Diverse functionalities can be bestowed by substituting the counterions of the charged framework with identically charged functional species, which broadens the horizon in the design of MOFs adaptable to a demanding environment with specific functionalities. 相似文献